Piston



N0V- 19, 1929- v.1. FLAMMANG ET AL 1,7356-,001

'PIsToN Filed Jan. 16, 1925 particularly to trunk pistonssuch as` are used A Patented Nov. 19, 1,929 .jj

" UNITED s' JOHN FLAMMANG, or UNIVERSITY CITY, AND fPnRcY L; isowsnnor sT. Louis, MIssOURI, AssIGNORs, 'BY MEsNE ASSIGNMENTS, To THE STERLING CORPORATION, or WILMINGTON, DELAWARE, A CORPORATION or DELAWARE 1 y e, f

Application led Januaryr This invention pertains to` pistons and more in internal combustionl engines.

,i In some types of trunk pistons used in internal combustion engines the piston is constructed of a light material such as aluminum or its alloys.V rlhis material, however, usually has a coefficient of thermal expansion greater than thatof the cylinder Vin which it Works. Consequently the piston is formed with certain portions somewhat larger than the cyllinder bore and is then cut or slotted appropriately to form bearing parts which are held in resilient contact with the cylinder wall by the spring of the metal. l/Vithv such a con-l struction the slots or cuts, which extend entirely throughl the piston skirt, accumulate oil by the splash of oil from the crank case.

. The oil-collected in these slots, however, may

i usually have sharp scraping edges and may not be effectively distributed on the cylinder wall, on account of the fact that such slots be positioned sothat they bear against the y cylinder wall withl considerable pressure.

'1 One of the objects of this invention, therefore, is to provide ysucha piston with means for distributing the accumulated oil over the cylinder wall.

Another object is to ,provideV means for draining the oil from 'the slots in the piston skirt.y f

Y Further obje/cts will appear from the following description -takenin connection with the accompanying drawing in which:

Figure 1 is a Vview in elevation showing. alpiston embodying this invention;

f Figure 2 is ia transverse section of the'pist ton shown in Figure 1, taken at right angles f ,to` the wrist pin' bearings;

'type illustrated Figure Sfis afragmentary sectional view` the grooveson. j the bearing facethereofgand .F'gure .Lis a fragmentarysectional i showing the Linder Wall. i l i Y Figure-bis an enlarged detail' of theskirt. Referringnow to the drawing, lFigureV 1, illustrates trunk piston preferably, lof i the in application' -l Serial #693,511liled'February 18, 1924,and having ,e

16,1925. seriaiNo. 2,836.

a head 1 provided near the head with pack-'1 ing ring grooves 2, and provided with an eX- grooves 2. The groovev communicates, by means'of a series of holes d drilled through the piston skirt, with the interior of thepisf ln accordance with this invention the `pis-g ternal annularoil groove 3 just below thering i `'ton -is constructed of a light material such.

vas aluminum or its alloys and inf-order to provide forexpansion. thereof the skirt is slotted with a series of longitudinal slots 5 Joined by transverse-slots 6 traversing Vthe, bearing face of. the piston. That portion'of the skirt adjacent thertraverse Aslots 6` is formed somewhat larger than the cylinder bore, while the ends of the piston are formed v "slightly less in diameter than the cylinder bore. It will be seen thatthis construction] provides that the bearing I'acesadjacent the slots 6 will bear with a resilientpressure against the cylinder walls, and that this bearing will be maintainedfat` all temperatures..

lThat portion ofthe skirt which lies opposite l the ends of the wrist pin bearings maybe relieved so as to provideshallow recessedv por not Contact with the cylini i v tions 7 which do der wall. I

A series of shallow Voil grooves are cut in-` the bearing face of the piston and extend Vlongitudinally therealong but at Van inclination to the aXis of the piston. These grooves connect with the transverse slots 6' and alsov with the annular groove 3 at the upper end of the piston and extend downwardly to theend of the skirt. In lthatportion of the'v bearing face of the piston which extends" below the recesses 7 short grooves 9 are cut connecting thoseA recesses with theend ofthe s'kirtJ/These v' grooves may be inclined ,similarly :to the grooves 8. g `V r 'Inthe operation of this piston the interior thereof will ordinarily be oodedwith oil by the splash from the crank-case. This will cause' the oil lto collect in the slotsv and 6. yNow theoil will not readily flow from the horizontal slots 6 to the cylinder walls but willrather v flow toftlievertical slots 5 'and hence tothe annular groove 3 from which it findsl its way to the Acombustion chamber. The

t holes 4: do not effectively drain the oil because during the intake or suction` stroke the air Vin the lhollow piston is'un'der compression and theholes 4 are necessarily small. 'lhe result is therefore ilow or um inGWo-foil a a l y b I tothe combustion chamber. A

e 'vlheprovisionofthe shallow ,grooves 8 and 9, however,l remedies such detect. Y As vthe bearing tace is in close contact with the cyl- V inder wall 10 as illust-rated in Figure the oil collected. in the grooves 6, and even in grooves 3 and 5 and space y-7-,`-will:find its lway to the ,groei/'es 8 and 9 and will pass into said vgrooves by capillary act-ion.y Then the-piston Y has been running a while there will, therefore,

- be providedy at intervals around the piston -shallow reservoirs of oil ormedby the grooves 8l .The oil in these grooves is in contactrwith the vcylinder ,wallfand will,A as the piston 'nieves to and iro, he spread over the cylinder Vlsurface and perform a lubricating `function K y and will not iow into the cornhiistion chamber 1 tio forni carbon. Y

These'grooves 8 and 9 thus provide means for distributing the-'oil over-the cylinder wall to lubricate the-piston; VAs :the oil is dis- Vtributedit is constantly replenished in the grooves 8 and `9 Aon account or their connection with the slots and 5 and also with the annular'groovefandspace V7. It will also be noted vthat the gro`oves-8` and 9 are open at `both ends ,so thatcirculation of oil may take place ltherethrough. V Consequently the possibility Vof oil vbecoming stagnant in thesegrooves 1s avoided'. Therefore5--with a continual freshnsup'ply' of oil in these grooves there islittle chance for the o'il Vbecoming heated to the poiiitofcarhonization,` 'The 'inclina-f tion of the of-rooves provides :for distributing oil over a s'ubs'tantialzvextent laterally of the cylinder wall. VIt will also he understood thatthe rapid reciprocation of the piston will tend' to work the oil along thegroov'e's f8 by a sort oit pumping actien which maintainsa flow through these 3 grooves andob'viates the o' stagnation of oil in the slots 5 and Sand the VIt will 'continual circulationof oi'lto prevent stagna- 'proper by abeveled portion 12. The external the skirt. Two bearing points for the piston are 'thus-provided, one fat its niiddlep'ortion vande-one at :its lovverfrirn?V Thefrimjinay 4 be seen, therefore,V thatthis iuvenY-i Vtion provides simple andinexpe'nsive means' i HVfor 1'distrilouting the oilfc'ollected inthe slots G onth'z'e' cylinder surface and to promote a ing through the rim and substantially through the flared portion 12. This split or tht' rim renders the-saine resilient, that it will give with changes on temperature `of ythepiston. The oil -igrooves 8 and 9l vpass through the iiared portion or the rini so as'to permit theoil to. pass therethrough-,es previously described. i f n if, y v In the detail or Figure 5 aswell as in the other figures the flare of the skirt and rim are greatly exaggerated inorder to show them distinctl In practice these will be only a few'thousandths of an inch over the rigid portions ot thepiston.

There is `,thus provided a piston which has resilient bearing portions at mere thanene point along its skirt; These portions' are inade with enlarged diameters iso' as yto have iirni hearing when the piston ,is cold and are resilient so as to be able-to adjust themselves to changes intemperatureas the pieten heats u i f f pit is obvious that variouschanges may he made in the details of construction :without departing from the `spirit of v-this invention; it is tov be understood, "therefore, fthatlthisinvention is notto be limited to the specific de- .tails shown and described, Having" thus described the'inve'ntionf'what isclainiedis: 'A "`1 l. A trunk piston having askirt'provided with a transverse slot, the hearingitace'having a shallow oil -distributingfgroeve ttherealong and connecting with Vvsaid*slet, fandV vmeans Vto establish c'onirnunicatin between a point remote fromV thelslot;

2. A trunk pistonhaving askirtprovided with a transverseslot,v theb'eaiingrace hav# ing an inclined shallow oil :distributing ygroove therealong and connecting with sai-d slot. Y- y t A trunk vpiston having 'a ring-*groove thereon and ashallow oildistrib'uting `groove therealongfand connecting. said means n.with

ASaid*annularoil'groove.

' Ll. A trunk piston havinga skirtprofvided 1further be split at intervals by slots 13 extendsaid groove andthe interior of the piston at with a transverse slot andwith -a longitudiynal slot connecting therewith; thebearing Y face having a s liallow'oil distributing gi-o'ove and connecting with one'orsaid therealong slots. Y

' A trunk pist'oiifhaving-aringgroovnd an annular oil 'groove' therehelov'f` connecting with fthe interior ofthe piston, a-'skirt having a transverseand a longitudinal slo'tfcofinectiH ing therewith,V the bear-ing tace fthe'piston having an oil` groove the'rez'iflo'ngv .and connecting with one of said slo'tsand" withifsai'd annular oilgroove.

L i A trunk piston aslrirt-lprovided ias I' with a transverse slot and ya longitudinal slot connecting therewith and terminating short of the end of the skirt, thereby to provide a resilient bearing surface for the piston, and a flaring rim split at intervals by` Slots terminating short of said longitudinal slot, thereby to provide a second resilient bearing surface for the piston. n Y

7 A trunk lpiston having a skirt provided with a transverse slot and a longitudinal slot connecting therewith and terminating short of the end of the skirt, thereby to provide a resilient bearing surface for the piston and aV flaring rim split at intervals by slots terminating short of said longitudinal slot, thereby to provide a second resilient bearing surface for the piston, said skirt being relieved between said bearing surfaces.

8. A trunk piston having a ring vgroove and an annular oil groove therebelow connecting with the interior of the piston,v a skirt transversely and longitudinally slotted to provide voppositely extended substantially rectangular sections, the bearing face of the piston having an oil groove therealong and connecting with one of said slots and with said annular oil groove. l y

9. A trunk piston having an annular oil groove adjacent the head thereof perforated at intervals to communicate with the interior of the piston, and having a skirt slotted to provide longitudinally and Voppositely extending rectangular sections, the bearing face of the piston having an oil groove therealong extending from one of said portions to the other and communicating with said annular oil groove.

In testimony whereof we ax our signatures this 22nd day of December, 1924.

JOHN FLAMMANG. PERCY L. BOWSER'. 

